1. Field of the Invention
The invention relates to a process for the preparation of a prepolymer amide, having a degree of polymerization within the range from 5 to 20 (number average) from a C.sub.12 -aminocarboxylic acid lactam by hydrolytic polymerization at an elevated temperature and elevated pressure.
2. Discussion of the Background
The preparation of prepolymer amides from aminocarboxylic acid lactams at an elevated temperature and under elevated pressure is known in principle.
Thus, Japanese Published Specification No. 59/164,327 describes a method of preparation of polycondensates from lactams having 7 to 12 members within the ring in a temperature range from 220.degree. to 280.degree. C. and under pressure ranging up to 10 bar. This choice of parameters leads to unsatisfactory results with respect to the space/time yield with C.sub.12 -aminocarboxylic acid polycondensates.
Further, a process is known from Japanese Published Specification 60/41,647 in which temperatures in the range from 295.degree. to 370.degree. C. and a water content from 2 to 50 percent by weight are used.